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1.
Summary A method is described for the determination of traces of lead and copper in foods by a microcomputer-processed atomic absorption spectrometry with a molybdenum micro-tube atomizer. Accurate results of lead and copper are obtained by atomization in the presence of thiourea. Thiourea contributes to a highly reproducible atomization profile and reduction of interferences from concomitant elements in foods. Solid samples are digested with nitric acid in the Uni-seal decomposition vessel, while liquid or water-soluble samples are directly atomized.
Bestimmung von Blei- und Kupferspuren in Lebensmitteln durch elektrothermische AAS mit einem Metallzerstäuber
Zusammenfassung Ein Verfahren zur Bestimmung von Blei- und Kupferspuren in Lebensmitteln mittels mikrocomputer-gesteuerter AAS mit einem Zerstäuber aus Molybdän wurde beschrieben. Die Zerstäubung in Gegenwart von Thioharnstoff gibt genaue Resultate. Dieser führt zu einem gut reproduzierbaren Zerstäubungsprofil und setzt die Störung von Begleitelementen herab. Feste Proben werden mit Salpetersäure aufgeschlossen, flüssige oder wasserlösliche Proben werden unmittelbar eingesetzt.相似文献
2.
Syntheses of 3-substituted indazoles and benzoisoxazoles were efficiently accomplished with the aid of Pd-catalyzed intramolecular carbon-nitrogen and carbon-oxygen bond formations. The catalyst system described herein allows the cyclization to proceed under very mild conditions and thus could be applied to a wide range of substrates with acid- or base-sensitive functional groups. A total synthesis for the indazole ring-containing natural product nigellicine is also described. 相似文献
3.
M. Suzuki K. Ohta T. Yamakita T. Katsuno 《Spectrochimica Acta Part B: Atomic Spectroscopy》1981,36(7):679-686
The processes of atom formation and dissipation in a molybdenum micro-tube atomizer have been studied to obtain information on the reaction involved. Vapor temperature was found to be close to atomizer surface temperature. Appearance temperatures and activation energies were obtained for Al, Co, Cu, Mn, Pb, Sb, Se, Sn and Te in argon and argon-hydrogen atmospheres. The atom formation processes are divided into two groups : the reduction of the metal oxide followed by the atomization of free metal, and thermal dissociation of the metal oxide. Hydrogen significantly changes atom formation processes for some metals compared to those in pure argon. The dissipation process of atoms from the micro-tube atomizer appears to be purely gas-phase diffusional. 相似文献
4.
Tsuneo Okubo Daisuke Suzuki Tomoyo Yamagata Akihiro Katsuno Masashi Mizutani Hiroshi Kimura Akira Tsuchida 《Colloid and polymer science》2011,289(7):807-816
Drying dissipative patterns were observed at 25 °C, 33 °C, and 45 °C on a cover glass, a watch glass, and a Petri glass dish
during the course of dryness of colloidal crystals of the thermo-sensitive gels of poly(N-isopropylacrylamide) (PNIPA). Two kinds of broad rings, i.e., transparent ring at the outside edge and the ring in the inner
area from the edge, were observed. Sizes of the former were the same as those of the initial liquids irrespective of gel concentration,
whereas sizes of the latter decreased as gel concentration decreased. These broad rings were composed mainly of the monomeric
and the agglomerated gel particles, respectively. Formation of the monodispersed agglomerated particles and their ordered
arrays in the inner area of the dried film were observed especially on a Petri glass dish and a watch glass. The important
role of the electrical double layers formed around the agglomerated particles is supported for the ordering of the agglomerated
particles. The essential differences in the drying patterns between PNIPA gel spheres and the typical colloidal particles
did not appear. 相似文献
5.
Da-Bing Li Takuya Katsuno Keisuke Nakao Masakazu Aoki Hideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2006,290(2):374-378
Influence of Si doping on the optical and structural properties of InGaN epilayers with different Si concentrations was investigated in detail by means of high-resolution X-ray diffraction (HRXRD), scanning electron microscope (SEM), Cathodoluminescence (CL) and photoluminescence (PL). It was found that a small amount of Si doping in InGaN could enhance luminescence intensity, improve the crystal quality of InGaN and suppress the formation of V-defects in InGaN. Further investigation by CL showed that V-defects act as nonradiative center, which lower the luminescence efficiency of InGaN. Based on above-mentioned results, one possible mechanism of influence of Si doping on the formation of V-defects in InGaN was also proposed in this paper. 相似文献
6.
T. Katsuno C. Godet J.C. Orlianges A.S. Loir F. Garrelie A. Catherinot 《Applied Physics A: Materials Science & Processing》2005,81(3):471-476
High-density tetrahedral amorphous carbon (ta-C) films have been prepared by nanosecond (17 ns) and femtosecond (150 fs) pulsed laser deposition (PLD) using fluences and repetition rates compatible with fast and homogeneous growth over large areas. Their optical properties were measured by spectroscopic ellipsometry from 1.0 to 4.7 eV and analyzed using a multi-layer Tauc-Lorentz model. In spite of very different ablation mechanisms, both PLD techniques produce high density bulk layers as revealed by a refractive index (n at 2 eV) of 2.7±0.1 for both fs-PLD and ns-PLD. Films are covered by a few nm-thick sp2-rich top layer which is denser and thicker in femtosecond PLD as compared to nanosecond PLD. The respective roles of low and high energies in the kinetic energy distribution of the incident carbon species are discussed in terms of densification and sp3↦sp2 configurational relaxation predicted by the subplantation growth model. The significantly higher optical gap found in the ns-PLD films is attributed to the larger contribution of energetic species with kinetic energies Ec≥200 eV, as revealed by time-of-flight optical studies. PACS 81.40.Tv; 81.05.Uw; 81.15.Fg 相似文献
7.
Haruki Koike Yohei Iguchi Kentaro Sahashi Masahisa Katsuno 《Molecules (Basel, Switzerland)》2021,26(16)
Amyloidosis is a term referring to a group of various protein-misfolding diseases wherein normally soluble proteins form aggregates as insoluble amyloid fibrils. How, or whether, amyloid fibrils contribute to tissue damage in amyloidosis has been the topic of debate. In vitro studies have demonstrated the appearance of small globular oligomeric species during the incubation of amyloid beta peptide (Aβ). Nerve biopsy specimens from patients with systemic amyloidosis have suggested that globular structures similar to Aβ oligomers were generated from amorphous electron-dense materials and later developed into mature amyloid fibrils. Schwann cells adjacent to amyloid fibrils become atrophic and degenerative, suggesting that the direct tissue damage induced by amyloid fibrils plays an important role in systemic amyloidosis. In contrast, there is increasing evidence that oligomers, rather than amyloid fibrils, are responsible for cell death in neurodegenerative diseases, particularly Alzheimer’s disease. Disease-modifying therapies based on the pathophysiology of amyloidosis have now become available. Aducanumab, a human monoclonal antibody against the aggregated form of Aβ, was recently approved for Alzheimer’s disease, and other monoclonal antibodies, including gantenerumab, solanezumab, and lecanemab, could also be up for approval. As many other agents for amyloidosis will be developed in the future, studies to develop sensitive clinical scales for identifying improvement and markers that can act as surrogates for clinical scales should be conducted. 相似文献
8.
Amyloidosis is a group of diseases that includes Alzheimer’s disease, prion diseases, transthyretin (ATTR) amyloidosis, and immunoglobulin light chain (AL) amyloidosis. The mechanism of organ dysfunction resulting from amyloidosis has been a topic of debate. This review focuses on the ultrastructure of tissue damage resulting from amyloid deposition and therapeutic insights based on the pathophysiology of amyloidosis. Studies of nerve biopsy or cardiac autopsy specimens from patients with ATTR and AL amyloidoses show atrophy of cells near amyloid fibril aggregates. In addition to the stress or toxicity attributable to amyloid fibrils themselves, the toxicity of non-fibrillar states of amyloidogenic proteins, particularly oligomers, may also participate in the mechanisms of tissue damage. The obscuration of the basement and cytoplasmic membranes of cells near amyloid fibrils attributable to an affinity of components constituting these membranes to those of amyloid fibrils may also play an important role in tissue damage. Possible major therapeutic strategies based on pathophysiology of amyloidosis consist of the following: (1) reducing or preventing the production of causative proteins; (2) preventing the causative proteins from participating in the process of amyloid fibril formation; and/or (3) eliminating already-deposited amyloid fibrils. As the development of novel disease-modifying therapies such as short interfering RNA, antisense oligonucleotide, and monoclonal antibodies is remarkable, early diagnosis and appropriate selection of treatment is becoming more and more important for patients with amyloidosis. 相似文献
9.
Tsuneo Okubo Daisuke Suzuki Tomoyo Yamagata Akihiro Katsuno Mikito Sakurai Hiroshi Kimura Akira Tsuchida 《Colloid and polymer science》2011,289(3):291-299
Morphology, phase diagram, and reflection spectroscopy of the colloidal crystals of thermo-sensitive gel spheres, poly (N-isopropylacrylamide) (224 nm in the hydrodynamic diameter at 25 °C) were studied. Giant colloidal single crystals formed
at very low gel concentrations. Critical concentration of melting of gel spheres (0.8 wt.% without ion-exchange resins) decreased
sharply to 0.01 wt.% as the gel suspension was deionized exhaustively with coexistence of the mixtures of cation- and anion-exchange
resins and increased substantially as concentration of sodium chloride increased. These studies demonstrated that the colloidal
crystallization takes place by the extended electrical double layers formed around the gel spheres in addition of the excluded-volume
effect of the gels. Most of the researchers including the authors have believed that the crystallization of the gel spheres
takes place by the excluded-volume effect, in other words, by the hard-sphere model, exclusively. However, the present work
clarified that the colloidal interfaces, which are inevitable for the formation of the electrical double layers, are formed
firmly between the water phase and gel spheres, though the gel spheres contain a lot of water molecules in the inner the sphere
region. 相似文献
10.
Hidetaro Yasumitsu Yasuhiro Ozeki Sarkar M. A. Kawsar Yuki Fujii Masayuki Sakagami Yuhsi Matuo Tosifusa Toda Hiroshi Katsuno 《Electrophoresis》2010,31(12):1913-1917
SDS‐PAGE and CBB staining are two of the most popular methods used for protein analysis. Although many reports that describe such staining methods have been published, these conventional protocols require several hours or days for staining and de‐staining. In this study we describe a recently developed, fast and sensitive CBB staining method that utilizes the staining solution of RAMA that consists of the low‐cost reagents: CBB R250, acetic acid, methanol and ammonium sulfate, and the destaining solution of water. Our method dose dependently detects 12 nanograms protein within 60 min and with a wide protein spectrum. Although the features of the dose‐dependent relationship depend upon protein amounts and protein types, for most of the protein samples tested, a linear relationship was observed in the region from 12 to 330 ng. Moreover, through further washing, the detection sensitivity of protein is enhanced and reaches a maximum at 1.4 ng and then gradually decreases in the de‐staining process. It has been shown recently through MS analyses that the sensitive colloidal CBB staining methods frequently result in artifactual methylations due to the strong acid and long contact during staining and the destaining processes. Such artifacts were reported to be reduced by the replacement of strong inorganic acid with acetic acid and because RAMA utilizes acetic acid and is in contact with the proteins for a short time during staining and de‐staining, it is expected that in vitro artifacts will be reduced. Finally, MS analyses of RAMA‐stained protein bands were revealed not to have been methylated. 相似文献